Mercury arc rectifier



April 1, 1947. c. K. ITTNER 2,418,305

,MERCURY ARC RECTIFIER Filed April l2, 1944 1, ji 55 J3\ E 2 f' l i: 3;l/ l/ l/l/l/ l if, 24 1| w ,l G e i D 1 I 1,. 14 S J5 1 l f D G m D G JOG I -Z G |1y. 8 D

N G 'AH f -S-Y`- vM-- Q O Oo 'I 0000@ I8 Figi fnvezdoz- CIL arles K I'nez' Patented Apr. 1, 1947 UNITED STATES PATENT OFFICE 9 Claims.

My invention relates to high-voltage, highcurrent mercury arc rectiflersand has for its particular object the construction of a rectifier ofthis character which prevents arc-backs produced by mercury splasheswhich tend to strike the anode. Such arc-backs represent at thebeginning a short circuit of the secondary of the rectifier transformerand result in service interruption. Many efforts have been made by theart to prevent splashing. Said efforts have been largely concerned withthe provision of bailles for preventing splashing.

A mercury arc rectifier comprises, in its most elementary sense, achamber adapted for highlevel evacuation and includes a centrallydisposed anode and a mercury pool cathode lying below and spaced fromthe anode. An evacuating conduit communicates with the chamber at apoint adjacent the top of the latter, and pumping apparatus is connectedtherewith to maintain such evacuation.

In operation a rectifier of this character depends upon the vaporizationof mercury, and it is necessary that the temperature of said chamber beregulated so as to produce condensation of said mercury vapors. Inasmuchas the chamber is subject to continuous evacuation, it follows that somesubstantial quantities of said mercury vapor are drawn into saidevacuating conduit leading exteriorly from the chamber. Said vaporsbecome cooled and condense, and if they ow back into the chamber, theydo so as liquid mercury which drops substantially the height of thechamber. Said now-back of mercury is not a continuous operation, but,normally, is initiated by vibration or jar. Thus, small cascades ofmercury flow back at intervals. Of course, the mercury could be trappedto prevent said flow-back, but this would rapidly deplete the mercury inthe cathode pool. The common practice, therefore, has been to providebaffles within the chamber to prevent splashing of said cathodes ofliquid mercury.

I have discovered that if the evacuating line is tapped at a low pointand a separate return line is provided, that the return flow of mercurycan be caused to ow into the chamber at a point well below thehorizontal plane of the anode to eliminate such mercury splashing andarc-backs. I preferably provide a return line which joins the evacuatingline at a point externally of the chamber and which communicates withthe interior of the chamber at a point below the normal level of themercury in the cathode pool. I preferably provide a U-shaped trap toprevent mercury vapors from being drawn through said return line,"

which would tend to ow counter to the normal: drain of liquid mercuryflowing therethru.

The details of my invention and an explanation of a preferred embodimentthereof are herein` after described with reference to the accompanye`ing drawing, in which the figure is a more or less schematic sectionthrough a typical mercury arc Pendently supported centrally of saidchambery from said plate or cover 2 is an anode head 3 sur-` rounded bya perforate anode shield 4. `The cathode comprises a pool of mercury 5held in a container 6 at the bottom of chamber |f A baille 1 liesintermediate said cathode and anode. Said.

shield and said baille together tend to serveas splash baias to preventliquid mercury striking the surface of the anode head 3 to permitelectron emission. Such a condition would result in an arc-back. It isrecognized in the art that every precaution should be taken to preventthe condensation or splashing of mercury on any parti It is true thatcontrol of the anode structure. devices are provided which are adaptedto pre- 4 vent damage to the rectiers. 4The action of said quence as itbecomes positive with respect to the cathode, and so current will owfrom it to the cathode. cathode spot to the anode bombards themercuryvapor, and as a result of this bombardment,

the mercury vapor is ionized and becomes a good' conductor.

It is necessary that the vaporized mercury be condensed and that thetemperature of the anode be maintained below the point of incandescence.Tank cooling coils 9 are, thus, arranged exteriorf` The movement ofelectrons from the ly of the chamber. Said tank cooling coils arepreferably sheathed by a cover Ill. Additional cooling coils II arepreferably provided for the cathode. The coils thus form, more or less,a continuous water jacket about the chamber for adequately cooling theentire structure and provide large condensing areas for mercury vapor.

It is essential that the chamber be maintained at a high level ofevacuation, and evacuating conduit .I2 `is in open communication with.the chamber at a point adjacent the top thereof. It is common practiceto connect a number of said rectiers in bank, and, thus, said evacuatingconduits are joined to a vacuum'manifold. 'Because of the fact that thecontents of the'chamber .are constantly being evacuated, it follows thatsome of the mercury vapor is ldrawn into the evacuation conduit and intothe shutoff valve I3. These lie exteriorly of the rectier and are atsubstantially lower temperatures than the interior of the chamber. Thevapor quickly becomes 'liquified Yand 'cools in said conduit rand insaid'shutofvalve.

v`It isessential Vthat the 'mercury pool be constantly replenished.Thus, it is common practice to arrange said conduit I2 and the shutoifvalve I3 `to drain into the interior of the cha-mber. Thus, vapors are`being pulled from lthe chamber, and `condensate flows back valong thefloor of said conduit. t is essential that said eva'cuating `conduitcommunicate with theichamber atapoint adjacent the top of'said chamber.

' Thus, when said condensate ows back into the l making-the evacuatingconduit a Ashort run leading downwardly from `the point I4 Aofcommunication with vthe chamber to the point I5 of communication with areturn conduit IS. VSaid return'conduit '16 preferably extends more orless vertically from the shutoff valve to a point adjacent the 4bottomof the chamber. Thus, any mercurywhich condenses in the customaryshutolTvalve-orlin'the evacuating conduit I2 is caused to flowdownwardly through the return conduit rather than laterally through theevacuating conduit. I preferably join the lowerend 16a of the return`conduitwith the interior of the chamber through a U-'shaped trap I1,preferably lying exteriorly of thechamber. Thus, 4said U-shaped traphouses a quantity of mercury IB in addition to being in communicationwith the pool of vmercury 5 forming a part of the cathode.

lIt is desirable that the evacuating conduit communicate `with theinterior of the chamber near the ltop thereof to minimize the amount ofmercury yvapor Withdrawn from the chamber. By fprovi'ding two lpoints ofcommunication-one withtthe' evacuating conduit and another with thereturn conduit-Iwould provide twofalternate paths 'through which mercuryvaporcould reach the shutoff valve. The quantity of mercury I3 lyingWithin said U-shaped trap eiectively bars the outward flow of mercury-vapor through the lower e-nd of the returnrconduit,"however. Thus,mercury Vapor leaves the chamber through the evacuating .conduit I2,land any1-quantity of mercury condensing in said evacuating conduit,said shut-01T valve or in adjacent connections tends to return to thechamber through the return conduit which has a straight vertical run.Also, the outward ow of mercury vapor from the evacuating conduit tendsto prevent any small particles of condensed mercury from being divertedto flow into the chamber at point I4. That is, the evacuating conduit4vI 2 is inopen communication-and is unrestricted by baiiles, traps andthe like, and thus the suction pump is entirely free to evacuate thechamber without loss of efficiency which would follow the use of bafflesor lother obstructions.

AI have not attempted to show in the drawing the various connectors andterminals by which electrical connections are made, because they will.readily be understood by persons skilled in the art. lMy invention isdirected only to the control of the flow of mercury vapors from thechamber and the return flow of condensed'mercury to keep the cathodepool replenish-ed without producing arc-backs in the rectier.

I claim:

l. The combination with a mercury arc rectifier of the characterdescribed comprising a chamber adapted for evacuation, anode and cathodeelements, the cathode element including a p ool of liquid mercury, lsaidrectifier being characterized by producing vaporization of said 'mercuryduring the operation thereof, vsaid pool-cf mercury lying below andbeing spaced substantiaily Yfrom the Yanode Velement, 'and l'a conduitleading from the interior of said chamber ito van evacuating devicearranged at the exteriort'he'reof, `said conduit `being in opencommunication with said chamber, or' a vertically extending `mercuryrcondensing Vand Lreturn conduit, communieating at itsl upper iend with'said evacuating-conduit intermediate the `ends "of'the'latter and withthe interior of said chamber, at Aa point spaced substantiallyAbe`low-the` point 'of communication of said evacuating conduit withsaid chamber.

2. The` combination 'with a mercury arc rectier vof 'the characterdescribed comprising fa chamber adapted for evacuation, `anode andcathode elements, the cathode element including a pool of liquidmercury, 'said rectifier jbeing characterized byproducing vaporizationoffsaid mercury during the voperation thereoffsaid 'pool ofV mercuryIlying below `and vvbeing spaced ysubstantially from the anode element,rand Ya conduit lleading from the interiorof said chamber to anevacuating device arranged at the exterior thereof, said conduit beinginopen-communi'cation -with said chamber, of a vertically lextendingmercury Vcondensing and returnconduit, fthe upper end of said return-conduit being in -communication with they 'evacuating conduit at 'apoint lying exteriorlyof lsaid chamber, and said mercury return conduitcommunicating with the interior of said chamber at its lower end.

`3. The 'combination with a mercuryarc 'rectier of the characterdescribed comprising a chamber adapted for evacuation, anode fandcathode elements, the cathode element-'including a pool of liquidmercury, lsaid rectifier `being characterized by producingvaporizationof lsaid mercury during lthe operation fthereof, .said `poolof mercury lying Ibelow and be-ing `spaced :substantially 'from theanode .element, land afconduit leading t'from 'the :interior .of `saidchamber to Aan fevacuating device `tarranged .at the eX-f terior`thereof, said lconduit being in openzcom-j munication with saidchamber, of a vertically extending mercury condensing and returnconduit, the upper end of said return conduit being in communicationwith the evacuating conduit at a point lying immediately exteriorly ofsaid chamber, and said mercury return conduit communicating with theinterior of said chamber at its lower end.

4. The combination with a mercury arc rectifier of the characterdescribed comprising a chamber adapted for evacuation, anode and cathodeelements, the cathode element including a pool of liquid mercury, saidrectifier being characterized by producing vaporization of said mercuryduring the operation thereof, said pool of mercury lying below and beingspaced substantially from the anode element, and a conduit leading fromthe interior of said chamber to an evacuating device arranged at theexterior thereof, said conduit being in open communication with saidchamber, of a vertically extending mercury condensing and returnconduit, the upper end of said return conduit being in communicationwith the evacuating conduit at a point lying exteriorly of said chamber,and at a horizontal level below the point of communication of theevacuating conduit with the interior of said chamber, and said mercuryreturn conduit communicating with the interior of said chamber at itslower end.

5. The combination with a mercury arc rectifier of the characterdescribed comprising a chamber adapted for evacuation, anode and cathodeelements, the cathode element including a pool of liquid mercury, saidrectifier being characterized by producing vaporizaticn of said mercuryduring the operation thereof, said pool of mercury lying below and beingspaced substantially from the anode element, and a conduit leading fromthe interior of said chamber to an evacuating device arranged at theexterior thereof, said conduit being in open communication with saidchamber, of a vertically extending mercury condensing and returnconduit, the upper end of said return conduit being in communicationwith the evacuating conduit at a point lying exteriorly of said chamberand at a horizontal level below the point of communication of theevacuating conduit with the interior of said chamber, the door of saidevacuating conduit sloping downwardly from said latter point to itspoint of communication with the mercury return conduit, and said mercuryreturn conduit communicating with the interior 0f said lchamber at itslower end.

6. The combination with a mercury arc rectier of the character describedcomprising a chamber adapted for evacuation, anode and cathode elements,the cathode element including a pool of liquid mercury, said rectifierbeing characterized by producing vaporization of said mercury during theoperation thereof, said pool of mercury lying below and being spacedsubstantially from the anode element, and a conduit leading from theinterior of said chamber to an evacuating device arranged at theexterior thereof, said conduit being in open communication with saidchamber, of a vertically extending mercury condensing and returnconduit, the upper end of said return conduit being in communicationwith the evacuating conduit, and said mercury return conduit terminatingat its lower end in a U-shaped trap communicating with the interior ofsaid chamber.

7. The combination with a mercury arc rectiiier of the characterdescribed comprising a chamber adapted for evacuation, anode and cathodeelements, the cathode element including a pool of liquid mercury, saidrectifier being characterized by producing vaporization of said mercuryduring the operation thereof, said pool of mercury lying below and beingspaced substantially from the anode element, and a conduit leading fromthe interior of said chamber to an evacuating device arranged at theexterior thereof, said conduit being in open communication with saidchamber, of a vertically extending mercury condensing and returnconduit, the upper end of said return conduit being in communicationwith the evacuating conduit, said mercury return conduit terminating atits lower end in a U-shaped trap communicating *with the interior ofsaid chamber at a point lying adjacent the level of the pool of mercury.

8. The combination with a mercury arc rectier of the character`described comprising a chamber adapted for evacuation, anode andcathode elements, the cathode element including a pool of liquidmercury, said rectiier being characterized by producing vaporization ofsaid mercury during the operation thereof, said pool of mercury lyingbelow and being spaced substantially from the anode element, and aconduit leading from the interior of said chamber to an evacuatingdevice arranged at the exterior thereof, said conduit being in opencommunication with said chamber, of a vertically extending mercurycondensing and return conduit, the upper end of said return conduitbeing in communication with the evacuating conduit, and said mercuryreturn conduit terminating at its lower endv in a U-shaped trapcommunicating with the interior of said chamber ata point lying bellowthe level of the pool of mercury.

9. The combination with a mercury arc rectifier of the characterdescribed comprising a chamber adapted for evacuation, anode and cathodeelements, the cathode element including a pool of liquid mercury, saidrectifier being characterized by producing vaporizaticn of said mercuryduring the operation thereof, said pool of mercury lying below and beingspaced substantially from the anode element, and a conduit leading fromthe interior of said chamber to` an evacuating device arranged at theexterior thereof, said conduit being in open communication with saidchamber, of a vertically extending mercury condensing and returnconduit, the Vupper end of said return conduit being in communicationwith the evacuating conduit, and said mercury return conduitcommunicating with the interior of said chamber at a point substantiallybelow the plane of the anode element.

CHARLES K. ITTNER.

REFERENCES crrcn The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,775,531 Kramer Sept. r9, 19301,348,279 Spagnola Mar. E, 1932 2,022,534 Braband Nov. 26, 19352,105,463 Cordes Jan. 1B, 1538 2,121,599 Kilgore June 21, 1938 2,265,608Marti Dec. 9, 1941

